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3.0 STRUCTURAL STABILITY <br />3.1 SUMMARY OF EXISTING DATA AND ANALYSIS <br />3.1.1 Embankment Design <br />As discussed earlier, the tailing facility was built in two phases, with the Phase II having a <br />Raise 1 and Raise 2. A typical section of the dam at final buildout is depicted in Figure 3 below, <br />as reproduced from the Phase II, Raise 2 Design Report (SRK, 1995). The embankment has an <br />overall downstream slope flatter than 314: IV with two 15 -foot wide benches associated with the <br />upstream raises that are built partially on tailing. <br />1+ 1 EXISTMG F..TION LN R SYSTEM <br />ID:TAL I) <br />(Reproduced from SRK, 1995) <br />EXISTING <br />DRAINAOE BLANKET & LNIER SYSTEM <br />$ECSI4M. -0.7v <br />r =MCRAU M FMBARKNI MLSe$48$-SEC710N Aa' <br />I'.50' <br />(DETAIL 21 <br />Figure 3 San Luis Tailing Dam Typical Cross Section <br />The Phase II, Raise 2 Design Report represents the final existing structural stability analysis of <br />the facility and examined the following cases: <br />• Static loading conditions, where the stability of the embankment is examined under <br />normal operating conditions. Presumably this was done with more water in the facility <br />than is present now, but as described below, this cannot be verified. <br />• Liquefaction triggering of the tailing whereby weakening or liquefaction of the tailing <br />could occur during an earthquake design event. <br />• Pseudo static stability analyses, which are an older method of examining stability under <br />earthquake loading. <br />• Deformation and post - liquefaction settlement analyses associated with an earthquake <br />event, whereby the embankment could undergo some deformation. <br />San Luis Project Miller Geotechnical Consultants <br />Tailing Dam Data Report 7 February 2014 <br />fE PHASE 3 RAJU 2 <br />— <br />IE <br />j F PI 11 RNSC 1 <br />V I <br />I0 <br />S <br />MATC RIAL <br />irPE I <br />RAISE 2 EL 3320' <br />RAISE I FL SSDO' G %NG 1PI� -W S EL E6LG''��' <br />P_NASE I EL 3590' �r <br />EXISTING <br />- <br />MATERIAL <br />TYPE I <br />"' -SEE DETAIL A <br />�L GEOTEXTILE <br />�1 <br />s <br />FASRIC <br />EXISTNI6 6RANUL AR <br />EMBANKMENT FILL `\ <br />�'- EXISTING <br />�- MATEM L <br />TYPE 2 <br />(MATERIAL TYPE AI <br />MATERIAL TYPE I <br />2' PROTECTIVE CCVER <br />NAATERIAL TYPE 21 <br />1+ 1 EXISTMG F..TION LN R SYSTEM <br />ID:TAL I) <br />(Reproduced from SRK, 1995) <br />EXISTING <br />DRAINAOE BLANKET & LNIER SYSTEM <br />$ECSI4M. -0.7v <br />r =MCRAU M FMBARKNI MLSe$48$-SEC710N Aa' <br />I'.50' <br />(DETAIL 21 <br />Figure 3 San Luis Tailing Dam Typical Cross Section <br />The Phase II, Raise 2 Design Report represents the final existing structural stability analysis of <br />the facility and examined the following cases: <br />• Static loading conditions, where the stability of the embankment is examined under <br />normal operating conditions. Presumably this was done with more water in the facility <br />than is present now, but as described below, this cannot be verified. <br />• Liquefaction triggering of the tailing whereby weakening or liquefaction of the tailing <br />could occur during an earthquake design event. <br />• Pseudo static stability analyses, which are an older method of examining stability under <br />earthquake loading. <br />• Deformation and post - liquefaction settlement analyses associated with an earthquake <br />event, whereby the embankment could undergo some deformation. <br />San Luis Project Miller Geotechnical Consultants <br />Tailing Dam Data Report 7 February 2014 <br />